Screen



Aug. 16, 1927.

H. J. REED ET AL SCREEN Filed April 1, 1925 2 Sheets-Sheet l Aug 16 1927 H. J. REI-:D ET Al.

SCREEN 2 Sheets-Sheet 2 Filed April 1. 1925 mum.

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Patented Aug. 16, 1921.-4

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A. Arrlwlirl! 11@ Avril f invention relates to -and more particularly, thoughl not exclusively, --to screens intended for screening (pulp in manufacture where the dilute is 5 to ascreen drum, usuall the interior thereof, and thereacted on y suitable devices, such, for example, as im elling blades,- the liner particles .being the y assed through meshes of the screen while t e coarser partic'le'sare discharged from the edgel thereof.

The invention will be best understood by reference to the following description when `taken in connection with the accompanying illustration of one specific embodiment thereof,w hile its scope will be more particularly pointed out in the appended c'lalms.

- In the drawings- Fig. 1 is an elevation in central longitudi;

nal 'section' showingthe principal working parts of a screen embodying one form of the invention;

Fig. 2 is an end elevation of the screen shown in Fig. 1;

fFig. 3 is a sectional elevation taken on the circumferentialv line 3-3n Fig. 2 5 and Fig. 4 is a cross sectional elevatlon taken on the line 4-4 in Fig. 2.

Referring to the drawings and to the em-v g bodiment of the invention whlch 1s there disclosed for illustrative purposes, the screen comprises opposite end members or casings 11 having feet 13 on which the screen is supported. The end members have inturned circumferential flanges l5 to which is se-l cured' an outer casing 17 whichis provided with detachable or sectional portions whichl maybe removed for pur oses of inspection or repair of the screen rum and other 1nterior parts. Within theA outer caslng 1 7 there is provided the perforated or foramlnous screen plate 19 in the form of a drum of any suitable and. usual construction secured at its ends to the inwardly projectlng flanges 21 on the end members. The space within the screen drum constitutes the screening chamber to which the diluted stock is fed. The annular space between the drum and the outer casing constitutes the screenedv stock chamber, the latter having the outlet v 23 through which the finer screened stock is discharged after having passed throughA the screen and into the screened stock ber.

cham- {'flatter'passdown throng f supply to the screening chamber, through the supply conduit 25 to the stock supply compartment 27 located on top of the outer cas- -1n 17, and is-thence carried-intoo posite cn s of the screening chamber t rough branched supply conduits 29 which turn downwardly at the outside of each opposite end casing 11.

The stock supply discharge passages an the impelling devices on opposite sides of the central vplane of the screen are of substantially similar construc- .tion and the arts on one side only need be described in etail. v

Referrin to Figs. 1 and 2, the stock at each end o the screen is supplied from the passages 29 to the exterior feed drum 31 and enters the .fixed annular feed spo whence it is discharged radiall and symmetrically to the screenin chamber through suitable supply orifices, erein com risin the annular slots35 a1 1d 37 suitably ocate ssages, the tailings l so as to distribute the stock supply len hl "wise ythe interior of the screening cham r.

lThe stock which enters the screening' chamber through the lftngitudinally distribvuted feed orifices is ac vu on by impeller blades 39 which assist in a vancing', it pro e'ssively over the screen 19 and in carrying rt- .forwardly and outwardly thereagainst under a continued pressure. The impelling devices, as well as the annular feed spout,

are herein shown for the-purpose of illustraltion as of the general construction described -in our contemporaneously led cri-ipendin'g application Serlal No. 19,609, iiled arch'Bl, 1925.

' In the screening screening chamber through the annular feed.

action the stool: enters the l,

ed on the driving shaft 43, are rotated andA calr'r the stock aroundand forward, forcing lt e thescreened stock er particles through the screen, which chamber and out through the outlet 23. The coarser particles or tailings gradually work toward the outer edges of the screen drum and are finally discharged into the tailings space 45 formed in the outer casing 17.

In the illustrated embodiment of the 1nvention we have provided means whereby the escape of the tailings from the tailings space is checked or retarded so that, being at the same time thinned more or less W1th shower water, they tend to return to the screening chamber and thus subjected to repeated thinning and rescreening, the coarser particles finally rejected and escapf ing from the tailings space being thereby separated from substantially all the-finer pulp or libre capable of passing througltthe screen. In the present form of the 1nvention this result is Secured by providing a tailings outlet located at a point or level s ubstantially above the bottom of the screening chamber, and herein above the longitudinal axis thereof, so that the tailings tend to accumulate and build up more or less of a back pressure or head, this not only facilitating their return to the screening chamber but assisting in maintaining the stock within the chamber in a state of liquid suspension. the rotary movement of the impeller blades and the head under which the stock is fed into the screening chamber being relied upon finally to force the coarser particles or slivers through the tailings outlet.

'llo this end the tailings space, during the normal operation of the screen, is closed at its bot-tom, escape for the tailings being provided through avslot or opening 47 (Figs. 2, 3 and 4) in the upper partof the casing, there being herein shown for that purpose two such openings in each end casing, one on each side thereof. Each opening is covered by a plate or cover 49 provided with a pipe connection 5l threaded into a raised boss on the plate, the pipe having suitable connection to a tailings discharge conduit, not herein shown.

lf desired, the height of the tailings outlet may be made adjustable and for that purpose we have herein shown the slot or opening 47 arc shaped in form and adapted to be overlapped for a considerable distance by the plate 49, the latter made in the form of a segment. The edges of the plate 49 are fitted in grooves formed by the raised overlapping Walls 5.3 of the casing, and to prevent leakage the walls of the casing atopposite ends of the slot 47 may also be provided with the packing strips 55 with which the overlapping ends of the plate engage.

The casing thus provides an are shaped guideway in which the plate may be moved to different positions of adjustment Within the range permitted by the length of the arc shaped slot 47, thus adjusting to di'erent heights the outlet pipe 5l -for the tailings space. The drawings show the tailings outlet 5l at its uppermost part but the range of adjustment may be made as great as desired in either direction, or the adjustable feature may be dispensed with entirely. When employed, however, it makes possible the variation in the height or set-back of the tailings to adapt the screen to different grades or classes of stock and to different conditions of operation.

The plate 49 is shown prolonged for a suilicient distance to provide the necessary overlap with relation to the slot in both extreme positions of adjustment. The prolonged portion of the plate enters a space between the casing and the supply chamber 29, as indicated. in Figs. 2 and 3. The end casing 11 may be provided with one or more clamping screws 5'6 to hold the plate fast in selected position of adjustment.

As the coars'er particles or rejects from the screening chamber rise to the level of the tailings outlet, they are subjected to a thinning action by means of a water shower. 'lhe latter may be located in any suitable location and, if desired, may extend entirely around the screen, but herein the shower water is delivered from a shower conduit 57 extending through the upper half of the circumferential tailings space in each end casing, such conduit being perforated at intervals to provide a shower throughout the entire upper half of the tailings space or the portion of the space above the level of the tailings. Due to the action of the shower and the concaved detlecting walls of the tailings space, the tailings `which are delivered from the screening chamber to the upper part of the tailings space are not only thinned by the shower, but tend to gravitate back into the screening chamber, so that the combined effect of the shower and the agitat' on of the tailings through the movement of the impellers tends to subject the coarser rejects tox a repeated rethinning and rescreening action. rlhis results in the escape from the tailings space through the elevated tailings outlet of coarser particles or slivers with substatially all of the liner libres eliminated therefrom and materially increases the edectiveness of the screen.

While we have herein shown for the purpose of illustration one specific embodiment of the invention and one specific form of screen, it is to be understood that useful application of the principle may be made to screens of Widely different type and form and that extensive deviations may be made from the form, arran ement and mechanical construction of parts erein shown, all without departing from the spirit of the invention.

Claims:

1. In an apparatus of the class described, the combination with a casing containing a having a screening chamber length screened-stock chamber, vfof a `screen wise., which the stock is is adapted fto' travel, and movable impellingmeansv within the screen- V ing chamber, said casing having a tailingsv space longitudinally separated from ,t 'e

drum and provided with an outlet above the' bottom of the screening chamber to provide'v an accumulation of tailings, f 2. In anapparatus ofthe class described, the combination with a casing containing a' screened-stock chamber, of a horizontally ar` ranged screen drum. having a screem chamber, rotary impelling blades within the screen drum, a tailings space Within the cas# ing and beyond the end of the drum and .said

ta11ings space having its outlet at a sub--4 stantial distance above the bottom of ,they drum to provide for an accumulation of tallings therein. i

3. In an ap aratus of the class described, the combination, with a horizontally .ar-:- ranged'screen drum of a casing surroundln the same and provided with a screened-stoc chamber, means for introducing diluted stock within the drum, movable impellingV means within the drum, a tailings space withinthe casing at each opposite end of the drum, and an elevated outlet for each tailings space at a substantial distance above the bottom of the drum. f i

4. .In an -apparatus of the class described, the combination with a screen drum, ot` movable impelling means Within the drum,` a tailings space at the end of the drum communicating with the interior thereof, and an outlet for the tailings therefrom arranged at such a height with relation to lthe drum as to tend to return the tailin s thereto.-

5. In an apparatus of the c ass described, the combination with a casing containing a screened-stock chamber, of ahorizontally arranged screen drum therein, rotar impelling means Within said chamber, sa1d casing having a tailings space at the end of the drum communicating with the interior ofthe drum and provided with an outlet located above the axis of the drum.

6. In an apparatus of the class described, the combination with a horizontally arf ranged screen drum, ofy a tailings space communicating with the interior thereof, a tailings outlet for said tailings s ace at a substantial Adistance above the ttom of the drum, and means ,in the upper part of said. tailings space fom-showering the 'tailings therein.

7.`An 'apparatusgvthe class described having a casing, a screen drum, a circumferential tailings 'space in the end of the -casin communicating with the interior of the rum, a shower pipe in the upper art of said circumferential yespace, and a tailing's outlet;A elevated' above the 'bottom thereof tom erein.

8.. In an apparatus of the class aeefibd,

the combination with a screen drumof a casing, a tailings space, a vertical elongated 'slot 1n the'casmg communicating with the point at which the stock 1s delivered to u flying the slot and containing .a tailings vouttailngs space, and an adjustable plate overlet communicating with the tailingsl space 9. The. methodbf screening bre stock which consists in feeding the same to the interior of a horizontal y arranged screen drum, acting on the bres by an impelling action from within to-.force the finer fibres through the screen and the tailingsthrough "the end of the drum-to a tailings space, and

causing the tailings to accumulate in said space to a height substantially above the bottompf the drum. v 10. The method of screening fibre stock which consists in f eedin 'the same to the interior of a horizontal y arranged screen drum, acting on the libres by an impelling action from within to force the nerbres through the screen and the tailings through the end of the drum to a tailings space, .causing the tailings 'to accumulate in said space to a height substantially above the bottom of the drum, and diluting or thinning the tailings in the tailin s space.

11. The metho of screening stock which consists in feeding the same 'to the interior -of a horizontall arranged screen drum, forcing the finer bre through the drum and `forcing tailings to return to the screen drum by repeatedly showering them and withdrawin themonly at a point substantially elevate above 'the bottom of the drum.

12. In an apparatus of the class described, the combination with a screen drum having a screening chamber to which the unscreened stock is fed, of impel'ling means within the screening chamber, a tailings space communicating with the interior of the drum in which the tailings are adapted to accumulate and from which they may return in art to the interior of the drum, an outlet or the tailings from said tailings space, and means for regulating the escape of the tailings.

13. In an apparatus of 'the class described. the combinatlon with `a casing having a screenin chamber provided with a screen and havmg movable impelling measadapted to traverse .the .stock lengthwise the screening chamber 4and force the finer fibres through the screen, said casing having a tailings chamber at the end `of the screen and said chamber having an outlet above the bottom of the screening chamber to provide an accumulation of tailings.

14. `In an apparatus of the class described, the combination with a screen drum, of a casingfcontainingthe` drum, said casing having a stoc k inlet from which the stock is caused to traverse the drum, and a tailings space at the end of the drum in which the tailings are adapted to accumulate and from which they may return in part to the drum.. said space having a tailings outlet adjustable as to height.

15. In an apparatus of the class described, th:` combination with a horizontally arranged screen drum, of a casing surrounding the E@ saine und provided with a screened stock chamber, means for introducing unscreened stock within the drum, rotary impelling devices within the drum, a tailings space Within the casing at each opposite end of the drum, and a. tailings outlet for each tailings space adjustableas to height.

In testimony whereof, We have signed our names to this s ecica'tion.

AROLD J. REED. CLAUDE L. SPAFFGRD. 

